By the year 1996 humanity has advanced enough to travel to the Moon and Mars, and establish settlements there. However, the Cold War is still going on, with ever-increasing tensions between the United States of America and the Soviet Union, and the threat of a nuclear war looms on the horizon.

But soon, an unknown menace befalls humanity: on Mars, the members of an exchange program funded by the United Nations to promote peace and dialogue between nations find themselves trapped in a crossfire between four mysterious humanoid robots - three of which begin firing on the exchange program's base, killing almost all of the students. Only a few people survive, but they find themselves isolated on an inhospitable planet that has become a battlefield. And, as if this wasn't enough, the pilot of the fourth robot, who has been trying not to involve civilians in the battle, actually presents himself to the survivors, introducing himself as [Albatro Null Eiji Asuka] and telling them that the Earth is being targeted for occupation by the faraway Grados Empire.